It can be but have you tried using a seat?

@@FalenAnjel2 that's true, there are tools to address most difficulties - seats to not overexhaust yourself while hanging (not to mention avoiding injuries), lanyard to stabilise your position, loops and steps (you can hang them on your ascender attached to the rope) to put your feet in. It all helps you in comfort and stability. But working on the trees you rarely hang in one place for long. Using this much hardware to stabilise yourself and get some comfort could easily double the time spent on the job, while in most of industrial climbing using this much hardware actually helps you make the job faster. I'm mostly working on telecoms, but I've done some trees in the past and this job is quite fast up there by itself, I guess there's more cleaning on the ground afterward. It all depends on the task.